Acid-base and spectroelectrochemical properties of doubly N-confused porphyrins

The cis-doubly N-confused porphyrin. H2N2CP. containing two adjacent confus ed pyrrole rings has been investigated from the Feint of view of its; acid- base and electrochemical behavior in dichloromethane. This novel porphyrin isomer can form two metal-carbon bonds in the, central core, stabilizing me tal ions in unusually high oxidation states. Furthermore, the two outside N -pyrole atoms remain available for acid-base and specific solvent interacti ons Protonation of the pyrrole N atoms proceeds according to two successive steps, while only a single deprotonation step has been observed in the pre sence of bases. Similarly, in the case of the silver and copper complexes t he protonation and deprotonation of the outer pyrrole rings have been detec ted, confirming the structure of the metalated species as M-III-HN2CP. The electrochemical reduction of the metal ions (III/II redox process) and oxid ation of the macrocycle ring have been detected respectively at -0.9 and 1. 4 V based on spectroelectrochemical measurements in conjunction with the ac id/base equilibrium studies. Additional waves observed around -0.5 and 1.3 V have been assigned to redox processes involving water molecules associate d with the doubly N-confused porphyrins.